3rd International Conference on Gait and Mental Function Washington, DC
February, 2010
JT Gwin2, Klaus Gramann1, D Ferris2, S Makeig1, Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California San Diego, La Jolla, CA
2 Gait Lab, University of Michigan, Ann Arbor MI
Electrocortical brain activity is coupled to gait cycle phase during treadmill walking
Recent findings suggest that the motor cortex is more involved in controlling steady speed human locomotion than previously thought. Indirect evidence comes from near-infrared spectroscopy studies indicating that cortical oxygenated hemoglobin is modulated by human locomotion speed. In addition, transcranial magnetic stimulation can suppress locomotor muscle activity via intracortical inhibitory circuits. Until now there has been no direct method for assessing correlations between brain activity and intra-stride walking dynamics.
The aim of this study was to determine if electro-cortical activity is temporally coupled to gait cycle phase during human walking. We used scalp electroencephalography (EEG), motion capture, a force-measuring treadmill, and lower limb electromyography (EMG) to record brain/body dynamics while eight healthy young adult subjects stood, walked (0.8 m/s and 1.25 m/s), and ran (1.9 m/s). We applied infomax independent component analysis (ICA) to parse EEG signals into maximally independent components that were then clustered across subjects by similarities in equivalent dipole locations and power spectra using EEGLAB routines (Delorme and Makeig, J Neurosci Meth, 2004). We calculated event-related spectral perturbations (ERSPs) and coherence between EEG and lower limb EMG activities.
Results from two subjects showed that beta-band and gamma-band changes in electro-cortical spectral power were time-locked to gait cycle phase. Periods of coherence between brain activities and lower limb EMG in the high-alpha and low-beta range were also dependent on gait cycle phase. These preliminary results suggest that electro-cortical brain processes are temporally coupled to locomotion motor patterns during steady-state walking. Supported by Office of Naval Research N000140811215.